Modernization of peasant agriculture creates dual ecologies; one an expanding, simplifying ecology, the other a shrinking ecology which becomes more complex at first, but ultimately degrades and simplifies. Within the dual ecologies, environmental changes stimulates two corresponding family adaptations: agricultural expansion and agricultural involution. In agricultural expansion, favorably situated or opportunistic families specialize uniformly, in parallel, to expand and intensify the raising of hybrid domesticates for regional and national markets. Agricultural expansion and modernization often degrade resources by wasting and despoiling resources used in traditional agriculture. In agricultural involution, non-competitive families manage a shrinking resource base. Agricultural involution often degrades resources by intensifying the use of traditional resources. Thus, both adaptations may degrade resources, amplifying competition and the pressure to evolve dual ecologies. By adapting to change, peasant farmers create more in the same direction. The hypothesis will be tested by observation of and interviews with members of a small number of families in the western highlands of Guatemala.